Exposure apparatuses for semiconductor processing are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an illumination source, a reticle stage assembly that positions a reticle, an optical assembly, a wafer stage assembly that positions a semiconductor wafer, a measurement system, and a control system.
In certain designs, one or more mover assemblies are used to move and position one or more optical elements in the optical assembly. The size of the images and features within the images transferred onto the wafer from the reticle are extremely small. As a result thereof, the precise positioning of the one or more optical elements is critical to the manufacture of high density, semiconductor wafers.